Can pneumonia be reliably diagnosed without x-rays?

Andrew M. Seaman

NEW YORK (Reuters Health) - Doctors may miss some cases of pneumonia if they rely solely on their patient's medical history and symptoms without the help of x-rays, according to a new study from Europe.

Dutch researchers, who published their findings in the European Respiratory Journal, found that of 140 patients who had their pneumonia diagnosed by x-ray, doctors initially thought only 41 of them had the severe lung infection.

"That's worse than flipping a coin," said Dr. Richard R. Watkins, who was not involved with the new research but has studied how doctors diagnose pneumonia.

People with pneumonia may have a cough, fever, nausea, vomiting, chills or chest pain. Under some circumstances, the infection can put someone in an intensive care unit and even turn fatal.

In 2009, the U.S. Centers for Disease Control and Prevention says about 1.1 million Americans were hospitalized with pneumonia, and about 50,000 died from it.

According to the researchers, led by Dr. Saskia van Vugt from the University Medical Center in Utrecht, most doctors use their best judgment in deciding who has pneumonia, because it's not possible to give everyone an x-ray to check for signs of the infection.

Little was known, however, about how accurate doctors are with their diagnoses, wrote the researchers.

For the new study, van Vugt and her colleagues used information collected between October 2007 and April 2010 on 2,810 adult patients of doctors in 12 European countries.

All of the patients came to the doctors' offices with a cough, but only 72 were initially diagnosed with pneumonia. All of the patients were then given a chest x-ray to see how accurate the doctors' diagnoses were.

Of those 72 initial diagnoses, the x-rays showed 31 did not have pneumonia. In the rest of the group, the researchers found the doctors missed 99 cases.

Overall, the doctors correctly diagnosed less than a third of pneumonia cases.

DOCTOR'S JUDGMENT v X-RAY

While catching only 29 percent of pneumonia cases seems alarming, Watkins said there may be differences between how doctors in Europe and the U.S. diagnose the infection.

He told Reuters Health that it's common for U.S. doctors to order x-rays if they suspect pneumonia.

In fact, joint guidelines from the Infectious Diseases Society of America and American Thoracic Society call for an x-ray to diagnose pneumonia, he said.

"The risk of radiation (from an x-ray) is very small versus the risks of a potentially life-threatening infection," said Watkins.

Dr. Joseph Rencic, a staff physician at Tufts Medical Center in Boston, told Reuters Health that getting an x-ray for a pneumonia diagnosis depends on the doctor.

"I wouldn't say every patient like this will get an x-ray, because it would be an overwhelming cost to society," Rencic, who was not involved with the new research, told Reuters Health.

In the U.S., a standard chest x-ray costs about $44 per patient.

Still, Rencic said patients shouldn't worry that their doctors may be missing their pneumonia.

"Basically these are probably benign pneumonias that they are missing. Doctors are pretty good at recognizing when pneumonia isn't present," he said.